I have a second question: On my same blog, I want to invite user 'asadultsadmin' to be an administrator on this same blog. I've sent this invitation, but apparently, upon accepting the invitation, it does not show the user as being added, let alone as an administrator.

Other threads to this issue I've seen, say to contact support directly. How do I do that?

I'm not seeing that the user has accepted the invite. Go to Users--> Invite New and you will see that the invite is still showing as "waiting". You might try resending it. Encourage the user to log into their WordPress.com account before clicking the link int he email.